Fixes indent in linkage specification blocks.

We now indent:
extern "C" {
int a;
}

without additional indent inside the extern "C" block.

llvm-svn: 173045
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index f8c454b7..f67cd8c 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -526,6 +526,10 @@
                "void f() { f(); }");
 }
 
+TEST_F(FormatTest, FormatsExternC) {
+  verifyFormat("extern \"C\" {\nint a;");
+}
+
 TEST_F(FormatTest, FormatTryCatch) {
   // FIXME: Handle try-catch explicitly in the UnwrappedLineParser, then we'll
   // also not create single-line-blocks.